It also said an independent commission was being created to assess WHO's widely criticised response to the epidemic, after the UN agency admitted last month it had been caught napping on Ebola and pledged reforms to avoid similar mistakes in the future.

WHO chief Margaret Chan "appointed Dr Bruce Aylward as the Special Representative for the Ebola Response with immediate effect and for the duration of the outbreak," spokeswoman Fadela Chaib told reporters.

Aylward, she said, will be responsible for coordinating all the different aspects of the agency's response to the devastating outbreak, which has killed nearly 9,000 people, almost all of them in Guinea, Sierra Leone and Liberia.

The Canadian national will also work closely with other UN agencies, the African Union and others "to support the Ebola affected countries (in their efforts) to control the epidemic," Chaib said.

The assessment commission will present an interim report in May and conduct a full review of WHO's handling of the epidemic once the outbreak is over, she said.

This "will help to guide future work in emergencies and outbreaks," Chaib said. The UN health agency, which only declared a "health emergency of international concern" in September, 10 months after the virus emerged has faced blistering criticism that its response has been slow and shoddy.

The outbreak appears to be waning, with the WHO last week announcing that the number of laboratory-confirmed Ebola infections had dropped below 100 new cases a week for the first time in more than half a year.

The agency said it has shifted its efforts from slowing the spread to stamping it out completely.

But Aylward warned late last month against complacency, stressing that the situation remained "extremely alarming". "There is no such thing as Ebola control. You've got to drive this to zero" cases, he said.